Power-meter.



'PATENTED JUNE 16, 19-08.

C. E. VAWTER, JR.

POWER METER.-

APPLIOATION FILED N016, 1907.

2 BHEETSSHEET 1.

as f 7 awvcwtoz No. 891,018. PATENTED JUNE 16, 1908". I

G. E. VAWTBR, Jn.

POWER METER.

APBLIOATION rum) Nov. 6-. 1901:.

2 SHEETS-SHEET 2.

. measures the real power and indicates this -GH.A.B,LES E. VAWTER, JR., OF BLACKSBURG, VIRGINIA.

POWER-DEEPER.

Specification of Letters Patent.

Patented dune 16, 1908.

Application filed. November 6, 1907. Serial No. 400,930.

4 and State .of Virginia, have invented certain new and useful Improvements in PowerMeters, of which the following is a specification. The primary object of this invention is the production of direct reading apparatus for the measurement of the driving power of any rotating shaft or other prime mover.

The so-called power meters and power scales hitherto known in the art measure simply the torque, and not the real power, which latter is the product of thetorque multiplied'b'y the angular velocity.

The apparatus embodying this invention directly, without the necessity of any mathematical calculations on the part of the user. This is accomplished inthe present invention by causing the voltage of a dynamo elec tric machine to vary directly assaid power varies by making the effective magnetic flux through the armature of said dynamo vary directly as the-torque along the shaft whose power is to be measured varies; causing the revolutions per second of said armature to vary directly as the angular velocity of said shaft varies, and connectin to the brush terminals of said dynamo avo t meter with a converted cable calibrated to read in horse power or other power quantities.

The speed of the dynamo armature may be made to vary directly as the a lar velocity of the shaft, the ower of which 1s to be measured by simply elting or gearin 'the armature shaft to the power shaft eit er directly or indirectly.

For causing the effective magnetic flux through the armature to vary directly as. the torque of the power shaft, I have shown herein two arrangements: One consists in making the field magnet and armature relatively movable laterally and varying this relative movement by means of a transmission dynamometer operatively connected to one of the said elements of the dynamo to move the same relative to the other element in such manner as to vary the effective field strength directly as torque is transmitted by the shaft. The other arrangement consists in causing the transmission dynamometer to shift the brushes on the commutator of the dynamo and thereby vary the effective magnetic flux directly as the torque transmitted by said shaft.

M invention consists further in the'novel com inationand arrangement of parts hereinafter described and more particularly pointed out in the accompanying clalms.

In order to more fully describe my invention reference will be had to the accompanying drawings forming a part of this specification, wherein:

' Figure 1, is a side elevation of one form of apparatus, embodying my said invention; Fig. 2, a section taken on 1ine 22, Fig. 1, looking 'in,the direction of the arrow, and showing in diagram the electrical connections Fig. 3, a detail central vertical longitudinal sectional view of parts of the torque transmission dynamometer shown in Figs. 1 and 2; Fig. 4, a view partly in central vertical longitudinal section and partly in elevation of a modification of the torque transmission dynamometer shown in the preceding figures; Fig. 5, a view partly in end elevation and fragmentary section of another form of apparatus embodying my said invention; Fig. 6, a fragmentary-detail top plan view of the electric generator shown 1n Fig. 5, and Fig. 7, a diagram to'illustrate the principle of t e apparatus shown in Fi s. 5 and 6.

Referrin first to t e form of my invention shown in igs. 1 to 3 inclusive, 1 represents a shaft transmission dynamometer, comprising two abutting shafts 2 and 3 journaled in alinement in sultable bearings 4 and 5 supported by pillars 6 and 7 resp ectivel mounted on a suitable base 8. hese s afts are free to rotate relatively to each other, but are prevented from relative lateral movement by a split collar 9, which incloses rings or flanges 10 and 11 on the abutting ends of said shafts. See Fig. 3. These rings ma be shrunk on said shafts, integral therewit or made fast thereto in any other desired way. On these shafts are mounted two cam clutch members 12 and 13 respectively, the cam faces 14 of which normally interlock'as shown, The member 13 is made fast on shaft 3, as to relative movement both longitudinally and angularly, b pin 15; while member. 12 is free to'move ongitudinally of shaft 2, but is held against rotation relative thereto by means of key 16.

A spiral spring 17 surrounds the shaft 2 nal movement.

30 members.

'55 made fast to the bearing pi and is normally under compression between the member 12 and a flanged collar .18 made fast on the shaft 2 as by pin 19.

An annular flange on the member 12 5 formsa chamber for one end of the s ring 17 and also a support for one end of a s eeve 21 which fits over the outside thereof and is made fast thereto against longitudinal movement with respect to the cam member 12 by- 10 one or more bolts 22 which extend intoan go connecting said s afts to the source 0 power and the driven shaft respectively, or vice versa, or the dynamometer may be placed directly on shaft whose ower is to be measured. It will therefore e seen that as long as the shaft 3 offers no appreciable resistance to the rotation of shaft 2, ower will be trans? mitted from shaft 2 to s aft 3 through theclutch members 12 and 13 without any relative angular displacement between said When, however, there is a load on shaft, 3, this will cause a relative angular displacement between the members 12 and 13 which will vary as the torque along said shafts varies. Since the abutting faces of the members 12 and 13 are cams this .angular displacement between said members will cause them to se arate, the member 12 traveling longitudinally tension of the coil spring 17, to the eft, Figs.

1 and 3. The member 13 cannot move longitudinally of shaft 3 because it is held by pin 15. The movement of the member 12 transmits a lateral movement to the sleeve 21, which movement varies directly as the torque,

transmitted along saidshafts varies, or by any desired law depending upon shape of Angular movement of the earns, 12 and 13. sleeve 21 around shaft 2 may be prevented elther by the friction between rack25 and gear 26 or in any other suitable way.

A. rack 25 is made fast to the bottom of the sleeve 17 and meshes with one side of .a double sector gear 26 suitably mounted on a spindle 27 carried in supporting bars 28 ars 6 and 7. The other side of this sector gear meshes with. a rack 29 mounted to travel laterally in suitable uprights 30 and 31 which form a part of the frame work of a dynamo electrlc machine 32. This dynamo is provided with a magnet 33, having a permanent field, and this magnet is operatively connected to the rack 28 for movement thereb as shown, or in an other desired way, an is mounted to .trave on suitably supported guide rods 34 sition and that of mininium flux shown,

of the shaft 2 a ainst thecircuit 41 will be actually 0 and 35, which may pass loosely therethrough.- The armature 36 of the dynamo may be of any desired type, but is normally so disposed relative to the field magnet 33 that the effective magnetic flux therethrough shall be preferably zero. This is effected inthe case shown, in F-i' s. 1 mature on a on shaft 37, so that the armature pro er sha be wholly outside of the field of t e magnet 33. Itwill therefore be seen that as the sleeve 21 slides longitudinally of shaft 2 directly in' roportion as the torque transmitted along t at shaft varies, this movement may be utilized to vary the efiective magnetic flux through the armature 36. The maximum lateral movement transmitted by the cams of members 12 and 13 is suflicient to shift the magnet of the dgnamo far enough to the right to cause t e effectivefimagneticlfiux through the armature to be a maximum, and between this p13 t c said flux will vary directly in proportion .to the lateral shifting of the sleeve 21 or the torque along shaft 2. When desired to avoid a zero error, ma et 33 maybe moved proportionately fart er at starting by properly shaping cams 12 and 13. It is also necessary that the revolutions per second of the armature shall vary directly as the angular velocity of the shaft the power ,of which is being measured. I effect this in" the apparatus shown in Fi s. 1 to 3 by merely beltin a pulley 38, on t e armature shaft, to sha t 2, as by means of belt 39. Any other suitable means, however, may beemployed for effecting this connection.

The electrical connections are shown in Fi 2, where 40 represents a Weston standar direct current voltmeter or other voltmeter provided with a converted scale and connected across 0 en circuit 41 leading from the brush bin ing posts 42, 43 of the dynamo armature -36 which is preferably of the open coil type.

If the voltmeter is electrostatic, then .the Y en; but in case a voltmeter such for examp e as the Weston D. C. type is used, the voltmeters resistance is made so high as to make the effects in the dynamo armature due to current practically ne ligible; that is, substantially the same as the entire external circuit of the armature were actually open. The E I .loss in armature and reactlon of'same on field when on closed circuit will make errors which the open circuit will not. give.

The scale45 of the instrument 40 may be calibrated in horse power in any suitable way I dynamometer m a form especially adapted to be mounted directly on the shaft, the power of which is to be' measured. In this form of the dynamometer the power is and 2, by mounting the arn Fig. 4, I have/ shown the transmission 55 nected to the'brush holder 67 will shift'the transmitted to thelaterally movable cam clutch member 46 through a sleeve 47 mounted on shaft 48 whose power is to be measured. This sleeve is rotatable f on shaft 48, but is held from lon itudinal movement, thereon by means of spl it collar 49 which incloses a flange 50 on t e end of said sleeve and a ring 51 made fast on shaft 48. The cam member is held from rotation of the sleeve 47 and held normally underi compression between the member 46 on a flange 57-formed on the sleeve .47.. These springs are inclosed by a sleeve 58 madefast to the member 46 against longitudinal movement relative to member 46 by'screws 59 which extends into an annular slot or roove 59' on flange 46'. The member 46' 1s slidable on the eri hery of the flange 57. Power to drive the 3 applied at pulley 60 mounted on-sleeve 47'.

-In this form of the dynamometer, the said pulley, sleeve 47,-- sleeve 58, and clutch memers .46 and 54 are all preferably in split sections, as shown to permit them-to be readily placed upon a shaft. I

-' In F'gs. 5, 6, and 7 I have shown aform of my invention in which the eflectivemagnetic flux through the dynamo armature 1s varied directly with the torque of. the power shaft by shifting the brushes of the dynamo. In this form of apparatus the dynamo has a stationary permanent bipolar ma et 61, and a drum-wound upon 0 en 00' arma ture 62, the shaft 63 of WhlOh is journaled in suitable brackets 64. The brushes 65 and 66 are mounted in an adjustable brush holder 67 loosely mounted on the armature shaft'and made fast to a inion 68 which is also loosely mounted on t e armature shaft. This pinion is geared to the lower 'teeth of the sector 26, so that" as the .transmission dynamometer shifts, said sector will in turn rotate the conpinion 68 and this bein brushes 65, 66, thereby varying the eflective magnetic flux through the dynamo armature.

The operation b which the eflective magnetic flux throuh the dynamo armature is varied by shi ting the brushes will be clear from the diagram Fig. 7, where 69 represents one of the open coiLarmature windings each of which terminates in two commutator segments 70 and 71, located on ynamonieter may be diametrically op osite sides of the commutator. When the rushes 65 and 66 are in the position shown, the number of lines of force:

out by the armature winding will be a maximum, and when shifted 96, the magnetic flux through said winding will be zero when the commutator segments come in contact with said brushes. Hence by shifting the brushes through an arc of 90 the effective magnetic flux through the armature may be varied all the way from a maximum to zero. segments should be narrow, and the brushes should .contact'with only a small portion of the commutator, thereby throwing each coil .infor o'nly a-short time and through a very small arc. The number of commutator segments and the number of armature coils should be large in order to give a uniform E. M. F. for a given position of the brushes.

For this purpose the commutator.

Also, the ole pieces of the ermanent field magnet o the dynamo shou d be so shaped as to give a field in which the number of magnetic lines of force out by the active coil will vary directly as the angle through ,which the brushes are rotated.v

The armature shaft 63 may be driven through pulley 72 or otherwise geared to run at a speed which shall vary directly as the angular velocity of the shaft whose power is to e measured, varies. w The forms of transmission dynamometer which I have herein shown are good, butIdo not wish to be understoodas limiting my invention to any specific form-of transmission .dynamometer or 1n fact to any one specific way of varying the effective magnetic flux through the'armature of the dynamo except Where either of these may be specifical y claimed. I may also make other modifications and changes as to the construction of the apparatus without departing from the spirit of my invention. a 7

Having thus described my invention what I claim is 1. In apparatus of the character described,

the comblnatibn with a rotatable shaft, of a dynamo electric machine adapted to have the effective magneticfiux through its armature varied, operative connection between said shaft and a part of said dynamo adapted to vary the effective magnetic flux through the armature of said dynamo directly as thetorque transmitted along said shaft varies, means to.vary the speed ofv rotationiof the rotating element of said dynamo directly as the angular velocity of said shafttvaries, and Y a voltage 0 erated measuring instrument connected in clrcuit with the armature terminals of said dynamo andcalibrated to read in mechanical power. 3

2. A power meter, com'rising a transmiss1on dynamo'meter provi ed with means to connect the same to a shaft the power of i which is to be measured, a dynamo electric machine adapted to have the effective magnetic flux through its armature varied, operative connection-between a part of said dynamo and said dynamometer to vary said flux directly as the torque'of said dynamometer varies, means to vary the speed of rotation of the rotating element of said dynamo directly as the angular velocity -of said shaft varies, and a voltage operated measuring instrument connected in circuit with the armature terminals of said dynamo.

3. A power meter, com rising a transmission dynamometer provi ed with means to connect the same to a shaft the power of i 7 which is to be measured, a dynamo electric machine having a constant magnetic field and provided with means whereby the efiective magnetic flux through its armature may be varied, o erative connection between a 'part of'said ynamo and said dynamometer to vary said flux directly as the torque ofsaid dynamometer varies, means to vary the speed of rotation of the rotating element of said dynamo directly as the angular velocity of said shaft varies, and a voltage operated measuring instrument connected incircuit with the armature terminals of said dynamo.

4. A power meter, comprising a transmission dynamometer, a dynamo electric machine adapted to have the efiective magnetic flux through its armature varied, operative vconnectionbetween a art of said dy'namo and said dynamometer, a apted to vary said flux directly asthetorque of said dynamometer varies, driving connectionbetween said dyna= mometer and the rotating element of said 7 dynamo,

instrument connected in circuit with the arand a voltage operated measuring that one of said members which is longitudi nally movable, a dynamo electric machine 'operatively connected through said gearing to said longitudinally movable member to have the effective magnetic flux through its 4 armature varied by the movement thereof directly as the torque transmitted by said shaft, means to drive the rotating element of said dynamo at a speed proportional tothat of said shaft, and a voltage-operated measuring instrument connected in circuit with the brush terminals of said (1 amo.

In testimony whereof afiix my signature in presence of two witnesses.

CHARLES E. vAwTEa J'R.

Witnesses:

L. F. Sonnonnnn, C. S. MAs'r. 

